|
14 CONTRmUTION6 TO ECONOMIC OEOLOOY
<br />o Poison Cnnyon~ntion, shale beds cont.nin very little cnrbonn-
<br />ous material, and coal is present nt only n few places nt the hose.
<br />Allont. 50 t.o 100 feet nboce LLe contnet with the Ilntal formation,
<br />e Poison Canyon contains massive buff' to red nrkosic sandstone and
<br />ngloalcrnte beds and thiD yellow shale beds. The sandstone beds
<br />°o course to medium grained, and contain much fresh feldspar.
<br />onglomernte beds cmdnin pebbles of I,n•:wite, gneiss, and qunrtzitG.
<br />ost beds of sandstone and conglomerato are lenticular and cross-
<br />:dded, and where they crop nut they weather into cnvet•nous clifl•s.
<br />Ialn beds nro plastic. mul slightly silty and generally show' poor
<br />ssilit.y. The Poison Canyon formation ranges in thickness from n
<br />Iin edge in lluerfiulo Pnrk to about 2,500 feet directly south nntl east.
<br />~ East Spanish Penk.
<br />CUCHAHA FORMATION
<br />'fhe Cuchnrn fonnntion (1]ills, 1891) of probable early Eocene age
<br />Osborn, 1929, fig. 51) crops out in the trough of the basin, and ex-
<br />:nds from south of the Spanish Peaks into Ifuerfnno Park.
<br />lu•oughout most of the coal field the Cuchnrn formation overlaps the
<br />oison Cnuyon formntiol with, marked unconformit,y. Directly east
<br />nd northeast of East Spanish Penk the contnet between the Cuchnrn
<br />Id Poison Cnuyon formations appears to be conformable and trnnsi-
<br />onal, but owing to lack of exposures the true relations could not be
<br />etermined.
<br />The Cuchnrn formntiou is composed of red, pink, and white snnd-
<br />one beds interbedded with bright-red, gray, and tau clnyslone. The
<br />mulstone beds ore thin bedded to nulssive, p;u•nllel to cross stratified,
<br />Id fine to very coarse graiuerl. Rerl and pink snntlstone beds are
<br />onglomernt.ic at many places, nud are generally well consolidated.
<br />;Inystono beds are thin to (hick bedded, plastic, and rontnin very
<br />null nnwunts of silt. The thiclness of the Cnchnru fm•umtion is as
<br />Inch ns 5,000 feet in the center of the sedimentary basin on the north
<br />lope of 1Vesl. Spnnisb Pcalc.
<br />HUERFA NO(1) FORMATION
<br />Str:da that overlie the Cuchnrn fornultinn ou 1Vest Spanish Penk
<br />uxl in a smnD urea southwest of the peak (pl. 12) ore tentatively
<br />essigned to the ][uerfnuo forumtion (hills, 1888) of Eocene age (Os-
<br />Im•n, 1929, p. 7=1). 1[ills (1901, p. 2) correlated these rocks with the
<br />Iuerfnuo formation. IIc states:
<br />I,Ithologlcnlly, only the 6nsa1 zonr Is rumps ruble wFth the lypirnl beds nu
<br />IC llnerfnno Ricer, e•hlrh, hnlcecer, Is nreonmed tar by the dlRerenre 111 the
<br />hnrncter o[ the Inrnl drhrla ut. the Llwo oP drpO.itlun. Iu both Inenlitirs the
<br />eds rest upon the Curtin rn Ginuntion, ~chirh Outcrops rmnlnuously behceeu
<br />hem, and thus places thr foal Of their Idcullty nlnu+st beyond quegtlm+.
<br />i • RESOURCES OF TRiN1DAD COAL FIELD, COLORAD~ ~]Q,rj
<br />Later, however, 1Villis (1912, p. 758) concluded offer n brief recrnl-
<br />I naissnnce of this region "that the 1[nerfuno Lnke deposition did nut
<br />~ extend ns fur to the east nud south as l6e Sl»:nisb Pe;tks, :uul that
<br />~ variegated beds obserred there are of older origin.`' :Uthough difl'er-
<br />iug greatly in lithology from typical beds of the Ihterfnno fm•nudiou
<br />in IIuerfnno Park (.Iohnson, 1959, p. ]0.2), these strata are tentaticel}•
<br />assigned to the IIucrfano fm•nlntion until sedimentary nnrl paleonto-
<br />logical stndics are completed.
<br />The lowermost beds of the Huerfnno(7) formation seem to be wn-
<br />fornutble with the uppermost beds of the underlying Cuchnrn fornin-
<br />tion on the nm•th and east Onnks of 1lrest Spanish Penk. llowecer,
<br />south and west. of the peak the two foruuitimis are unconfm•mnble.
<br />1'he IIuerfnno(1) formation consists of interbedded, Ieuticul:u•.
<br />poorly soI•Ced beds of arkose and grn}'wncke conglomerate, cmtglonl-
<br />m•nt.ic sandstone, and siltstone with n few beds of clnyslone. Con-
<br />glomerate and conglomeratic sandstone beds very from reddish brown
<br />to tan to grey. The bedding is medium thick to nmssil•e and Icn-
<br />ticul:u•. Tm•rentinl crossbedding is eery distinct. 1'he nlntt•iz of
<br />conglomerate and conglomeratic sandstone beds consists of poorly
<br />sorted, angular to subrounded grains of quartz, feldspar, fcrl•o-
<br />magnesiml minerals, nntl rock fragments. Grains range in size from
<br />clay [o coarse sand, and are poorly to well cemented by clay, micro-
<br />scopic rock fragments, and silica. The coarse frngluents consist. of
<br />subrounrlerl to rounded pebbles, cobbles, and boulders of quartzite,
<br />gneiss, chert, sandstone, siltstone, clnystmle, and shale. Locnll}', red
<br />nurl green clay brills and stringers of ferromagnesian minerals ;u•e
<br />found in these beds. siltstone beds are Frny to reddish broicn, thin
<br />bedded, with isolated wellarounderl pebbles of quartzite. rear the
<br />base of the formation nuuq• cnlcnrcous nodules are fmuul within the
<br />siltstone beds, nutl irregular masses of siliceous, cooly material :uul
<br />scattered cnrbonnreous nuitter are locally present.. clnyslone beds
<br />~ nro brownish red, silty, plastic, and thick bedded.
<br />Although the 1{nerfiulo(?) formation consists mainly of con-
<br />glomerute and conglomeratic snntlstone beds, the rock units become
<br />more definitely conglomeratic upicard; the top of the fornuit.ion con-
<br />) twins boulders as huge ns 10 feet in diameter. The formation is np-
<br />prosiuultcly :1,000 feet. thiclr on the south flank of 11'est Spanish Peak,
<br />mul grades into a cmnples of sills nud nlehunorphosed srdinlent:u_c
<br />rocks that IS a550C111te(I with the 11'est Spanish Penk intrusive.
<br />UEP081T9 OF QlrA7•ERNAIiY AOE
<br />Deposits of alluvium consisting mainly of gravel rncer most. of the
<br />stream bottoms and valley flats. Landslide debris nud tahts coret•
<br />
|